1. Field of the Invention
This invention relates to a tube joint for the rapid and secure connection of synthetic resin tubes, resulting in an excellent water-tight system and fastening therebetween.
2. Description of the Prior Art
A tube joint for the connection of a flexible tube of plastics such as polyethylene to a fixed pipe is disclosed in Japanese Laid Open Publication No. 53-16915 (16915/1978), wherein as shown in FIG. 7, external threads 311 of the end portion of a connection cylinder 314, which has an internal groove 331 receiving a ring packing 310 therein, engage with internal threads 330 of a cap nut, so that the diameter of a clamping ring 313 positioned between the cylinder 314 and the cap nut 312 is reduced to thereby deform an area of the synthetic resin tube 317 in accordance with a groove 315 which is positioned in the circumference of a tubular core 316 inserted into the end portion of the tube 317. In order to attain an excellent water-tight system between the tube joint and the tube 317, the inner diameter of the ring packing 310 must be smaller than the outer diameter of the tube 317 so that the ring packing 310 comes into tight contact with the tube 317, resulting in the detachment of the ring packing 310 from the internal groove 331 to cause an inferior water-tight system.
Another tube joint is disclosed in Japanese Laid Open Publication No. 51-72221, wherein as shown in FIGS. 8 to 10, one end portion of a synthetic resin tube 322 which receives, in advance, a cap 320 and a nut 321 thereon is positioned onto a tubular guide 319 of a tube joint body 318 and then the nut 321 is screw-threaded with external threads 323 of the tube joint body 318, thereby decreasing the diameter of the cap 320 to attain a water-tight system between the guide 319 and the tube 322. However, the cap 320 comes into contact with the tapered portion 324 of the nut 321 in a large area, so that the tube 322 turns around the guide 319 together with the cap 320 as the nut 321 is rotated around the cap 320, resulting in a twisting of the tube 322 creating a constriction thereof.